945600 - Should allow interpolation between different-length background-position lists

Status: NEW

(Core :: CSS Parsing and Computation, defect, P4)

Description

[Boris Zbarsky [:bzbarsky]]

Right now we end up just bailing out from nsStyleAnimation::ComputeDistance if the two background-position lists have different lengths.  But if I read the spec right it should animate as http://dev.w3.org/csswg/css-transitions/#animtype-repeatable-list which should allow interpolation between different-length lists, right?

Comment 1

[Boris Zbarsky [:bzbarsky]]

A simple testcase:

<div style="background: url(http://www.mozilla.org/images/mozilla-banner.gif) no-repeat;
            animation: slide 15s linear infinite;
            -webkit-animation: slide 15s linear infinite;
            height: 200px"></div>
<style>
  @keyframes slide {
      0% { background-position: 0 0, 0 0; }
    100% { background-position: 200px 0; }
  }
  @-webkit-keyframes slide {
      0% { background-position: 0 0, 0 0; }
    100% { background-position: 200px 0; }
  }
</style>